Print shops generally convert printing orders, also known as print jobs, into finished printed material. Conventional print shops are usually organized in a manner that is functionally independent of print job complexity, print job mix, and total volume of print jobs. Typically, related equipment is grouped together. Thus, all printing equipment is grouped and located in a single locale. Similarly, all finishing equipment is grouped and located in a single locale.
Conventional print shops organize resources into separate departments, wherein each department corresponds to a type of process or operation that is performed to complete a print job. When a print job arrives from a customer, the print job sequentially passes through each department. Once the print job is completely processed by a first department, the print job gets queued for the next department. This approach continues until the print job is completed.
The application of lean manufacturing concepts to print shop can drastically improve print shop efficiency. In the lean processing, print jobs quasi-continuously “flow” through the shop or through its production cells—small parts of the job that have been processed on a given workstation are moved for processing on next workstation without waiting for the remaining part of the job to be completed on the given workstation. In preparing print shops for lean document production, an important component is evaluation of the production rates required for customer jobs to be delivered on time.
A conventional calculation (i.e., of so called “takt-times”) assumes that each job contributes to the demand rate uniformly within the time segment from the job arrival time through the time due. After summation over all jobs, the peaks of demand rates are used to estimate necessary resource capacities and current utilization. Depending on the job mix and demand fluctuations, the conventional calculation may lead to a substantial overestimation of the peak demand rates, and therefore of necessary capacities. These features are of a generic nature and can apply to any other lean production environment.
Additional complexity arises in the case of multiple resources, where a single resource capacity is not sufficient. Instead, a “family” of resources is utilized. When more than one resource is utilized, such resources can essentially “compete” against one another to satisfy the balanced lean workflow—decrease of one resource capacity can require increase of another resource capacity.